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Submitted by: Santosh pathak IAAS, Lamjung

Presentation on Leafminer

Scientific classification

Kingdom: Animalia

Phylum: Arthropoda

Class: Insecta

Order: Diptera

Superfamily: Opomyzoidea

Family: Agromyzidae

Subfamilies

•Agromyzinae•Phytomyzinae•Genus and species:Liriomyza sativae Blanchard

General information

•A leaf miner is the larva of an insect that lives in and eat the leaf tissue of plants. The vast majority of leaf-mining insects are moths(Lepidoptera), sawflies (Symphyta) and flies (Diptera), though beetles and wasps also exhibit this behavior

•The native country of this pest is USA (Florida). It was introduced probably along with cut chrysanthemum flowers during early 1970s to California, USA .

•The fly was accidentally introduced into Kenya around the same period.

•It is now very widely spread in most countries including Pakistan ,India and Nepal

• It is a polyphagous species affecting more than 78 annual plant species .

Introduction

•Adult leafminers typically look like small black and yellow flies, although some insects look more silvery-gray in color.

•The larvae look like very small, yellowish-colored maggots feeding on the undersides of the leaves.

•Check underneath the leaves for masses of tiny cream-colored, oval eggs and crush any eggs that we find.

•Once hatched, the larvae leave a winding, white trail behind as they feed, so keep an eye out for that symptom.

•The emergence of larvae takes place after 2-4 days.

•Then it feeds between the leaf surfaces, creating a meandering track or "mine

Identification

Eggs in the mine Maggot

PupaAdult

The severely affected leaves may drop.

Liriomyza leaf miner may act as vector of disease, kill seedlings, cause reduction in crop yields, accelerate leaf drop thus exposing fruits like tomato for sunburn and reduce aesthetic value of ornamental plants.

Maggots mines into leaves and causes serpentine mines drying and drooping of leaves.

Symptoms

The adult female makes punctures in the leaf tissue with its ovipositor for both feeding and oviposition.

The ratio of oviposition punctures to feeding punctures varies from 1:6 to 1:14.

The male also uses the feeding punctures made by females for feeding.

The larvae that hatch out from the eggs mine the leaf feeding on the mesophyll region leaving a serpentine structure and thus the common name.

Contd…………………..

Leafminer feeding results in serpentine mines (slender, white, winding trails); heavily mined leaflets have large whitish blotches.

Leaves injured by leafminers drop prematurely; heavily infested plants may lose most of their leaves.

If it occurs early in the fruiting period, defoliation can reduce yield and fruit size and expose fruit to sunburn.

Pole tomatoes, which have a long fruiting period, are more vulnerable than other tomato crops.

Leafminers are normally a pest of late summer tomatoes and can reach high numbers.

Contd……………………………………………………

Biology The lifecycle of leafminer is only 2 weeks in warm weather and 7-10 generation.

The developmental thresholds for eggs, larvae and pupae are estimated at 9 to 12˚c.

The combined development time required by the egg and larval stages is about seven to nine days at warm temperature(25 to 30˚c).

Another seven to nine days is required for pupal development at these temperatures.

Both eggs-larval and pupal development times lengthen to about 25 days at 15˚c.

At optimal temperatures(30˚c), the vegetable leaf miner completes development from the egg to adult stage in about 15 days.

Life cycle of Leaf miner

ManagementThe most important aspect of leafminer management is conserving their natural enemies, which are often killed by broad-spectrum insecticides applied for other tomato pests.

Reduce the risk of leafminer outbreaks by applying insecticides for fruit pests only when monitoring shows treatment is needed and by choosing insecticides that will not destroy the leafminer parasites.

BiologicalControlSeveral species of parasitic wasps, particularlyChrysocharis parksi and Diglyphus begini, attack leafminer larvae; left undisturbed, parasites often keep leafminers under control.

Cultural ControlCheck transplants before planting and destroy any that are infested; leafminers reach damaging levels earlier when infestations begin on seedlings.

Where a series of tomato crops is planted in the same area, we can reduce early infestations in a new crop by removing old plantings immediately after the last harvest.

Look for vegetable varieties that are less susceptible to leafminer infestation, such as tomato cultivars with curled leaves.

Don't plant any vegetables in areas where you've had previous leafminer infestations. Always remove any remaining old plants at the end of the growing season.

Organically Acceptable MethodsBiological and cultural controls as well as spray of formulation of spinosad are acceptable for use on an organically certified crop.

Chemical pesticidesIt's better not to use any type of chemical controls to manage leafminer infestations. Not only will the chemicals kill off the leafminer's natural predators, but the insects have developed a resistance to insecticides containing carbamates, pyrethroids and organophosphates.

Using any of those chemicals will likely make your leafminer populations increase in size.

If we feel that you must use chemical controls, then Avermectin, a microbially derived insecticide, seems to kill the leafminers but not their predators.

The University of California recommends spraying Spinosad to control leafminers on organically certified crops.

Mechanical control

Prune off and destroy any affected leaves on your infected vegetable crops.

Protect small seedlings by covering them with a protective cloth or a cold cap. Because leafminer adults are flying insects, covering your plants should prevent the insects from landing and laying eggs.

It is particularly important to protect your leafy vegetable crops such as lettuce and spinach because the feeding leafminers will damage the edible part of the plant.

Summary and conclusion Leaf miner is becoming major problems of vegetables especially in tomatoes growing areas. So it s population should be remain under the threshold level of damage by applying cultural, biological and physical methods.

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